Limitations on server cursors

You can call the mysql_stmt_attr_set() function in the C API on a server to implement the cursor feature.

A server cursor can generate a result set on the server. Only the rows requested by the client are transferred to the client. For example, if the client executes a query to obtain the first row, other rows will not be transferred to the client.

Observe the following limitations:

• Cursors are read-only. You cannot use cursors to update rows. Therefore, UPDATE WHERE CURRENT OF and DELETE WHERE CURRENT OF are not supported.

• Cursors cannot be maintained. In other words, a cursor cannot maintain in the opened state after it is committed.

• Cursors are insensitive.

• Cursors are non-scrollable.

• Cursors cannot be named. You can use a statement handle to obtain the cursor ID.

• Each prepared statement can open only one cursor. The number of cursors is the same as the number of prepared statements.

• If the prepared mode does not support a statement that generates a result set, you cannot use a cursor in this statement. Such statements include CHECK TABLE, HANDLER READ, and SHOW BINLOG EVENTS.